Having done my review of the year and already looking forward to 2008 (that's a statement of fact rather than a declaration of optimism), my eye alights on one of the highlights of January 1 on Channel 4. Shameless starts its fifth series. Well, I say highlights; I think it's been pretty rubbish since Fiona and Steve left. But Channel 4 is so keen on the show that it's ordered 16 episodes with a view to a slew more in series six. Well I say keen. Maybe I mean desperate. Of the series Channel 4 broadcast this year, few flew - Nearly Famous was entirely awful and Cape Wrath was hardly destination TV.

This wasn't a phenomenon confined to Channel 4. While there were many excellent one-off dramas, series foundered everywhere: BBC1's True Dare Kiss, ITV1's Whistleblowers and Talk to Me, BBC2's Party Animals, ITV2's Secret Diary of a Call Girl. None set the heather alight and only the latter has been recommissioned - and indeed sold to Showtime in the US. The sound of one hand clapping in appreciation is almost deafening.

This seems an awfully low hit rate to me. Can it be put down entirely to the quality, or not, of the individual series? Or has the time of the six-parter been and gone? Is the future one in which only one-offs, or at a push two-parters, and long-running series - which is to say, mostly American shows or jumbo runs of UK ones such as Shameless - prosper?